Anderton Boat Lift - Planning and Design

Planning and Design

By 1870 the Anderton Basin was a major interchange for the trans-shipment of goods in both directions, with extensive warehousing, three separate double inclined planes and four salt chutes. However, trans-shipment was time-consuming and expensive, and the Trustees of the Weaver Navigation decided that a link between the two waterways was needed to allow boats to pass directly from one to the other. A flight of canal locks was considered but discarded, mainly because of the lack of a suitable site and the loss of water from the canal that would have resulted from operating locks. In 1870 the Trustees formally proposed a boat lift between the waterways. The Anderton Basin was the obvious site for such a boat lift. The Trustees approached the North Staffordshire Railway Company, then owners of the Trent and Mersey canal, to ask if they would contribute towards the cost of the boat lift. However, this approach was unsuccessful, so the Trustees agreed to fund the boat lift themselves.

The Trustees asked their chief Engineer, Edward Leader Williams, to draw up plans for a boat lift. Leader Williams considered various ideas and finally settled on a design involving a pair of water-filled caissons, which would counterbalance one another, and so require relatively little power to lift boats up and down. A similar boat lift on the Grand Western Canal, completed in 1835, used chains to connect the caissons via an overhead balance wheel. However, this design required a very solid masonry superstructure to support the weight of the loaded caissons. Leader Williams realised that if he used water-filled hydraulic rams to support the caissons instead, then the weight of the caissons would be borne by the rams and their cylinders, buried underground, and a much lighter superstructure could be used. He may also have been inspired by inspecting a hydraulic ship lift and graving dock at the Royal Victoria Dock in London, designed by experienced hydraulic engineer Edwin Clark.

Having decided on a hydraulic ram design, Leader Williams appointed Edwin Clark as principal designer. The Anderton Basin, at that time, consisted of a cut on the north bank of the Weaver surrounding a small central island. It was decided to construct the boat lift itself on this island. The two wrought iron caissons were each 75 ft (22.9 m) long by 15 ft 6 in (4.72 m) wide by 9 ft 6 in (2.90 m) deep, and could each accommodate two 72 ft (21.9 m) narrowboats or a single barge with a beam of up to 13 feet (4.0 m). Each caisson had a weight of 90 tons when empty and 252 tons when full of water (because of displacement, the weight is the same with or without boats). Each caisson was supported by a single hydraulic ram consisting of a hollow 50 ft (15.2 m) long cast iron vertical piston with a diameter of 3 ft (0.9 m), travelling within a buried 50 ft (15.2 m) long cast iron vertical cylinder with a diameter of 5 feet 6 inches (1.68 m). At river level the caissons sat in a water-filled sandstone lined chamber. The above ground superstructure consisted of seven hollow cast iron columns which provided guide rails for the caissons and supported an upper working platform, walkways and access staircase. At the upper level the boat lift was connected to the Trent and Mersey canal via a 165 ft (50.3 m) long wrought iron aqueduct, with vertical wrought iron gates at either end.

In normal operation the cylinders of the two hydraulic rams were connected by a 5 in (130 mm) diameter pipe, which allowed water to pass between them, thus lowering the heavier caisson and raising the lighter one. To make adjustments at the start and end of a lift either cylinder could be operated independently, powered by an accumulator or pressure vessel at the top of the lift structure, which was in turn kept primed by a 10 horsepower (7.5 kW) steam engine. If necessary, the steam engine and accumulator could operate either hydraulic ram on its own, thus raising the caissons independently, although this would take about 30 minutes to raise a caisson from river level to canal level, as opposed to 3 minutes in normal operation.